1. Field of the Invention
The present invention pertains to a system for completing and maintaining horizontal extensions of vertical wells. The invention has particular application to offshore operations in which a number of wells may fan out from a common platform. The invention also has particular application to subsurface producing formations where it is advantageous to produce the formations by using laterally disposed wells. The invention is especially beneficial in removing bridges or otherwise cleaning sediments and debris from laterally disposed wells.
2. Related Art
A continuing objective in the petroleum industry is to increase the productivity of wells drilled into petroleum-bearing formations. Another continuing objective is to maintain well productivity and to reduce the need for expensive repairs and work-over operations. Although laterally disposed wells offer a number of advantages, they are often difficult and expensive to maintain. They are prone to bridging and plugging because of the deposition of sand, silt, frac proppant, formation particles and the like. These materials tend to accumulate along the bottom or lower side of lateral wells where they raft up into barriers due to fluid flow. As these barriers increase in size, they reduce the size of the flow passageway with resultant loss in production.
Cleaning or flushing accumulated sediments from laterally disposed wells can be very time consuming and expensive. This is especially true in pumping wells, where it is generally necessary to remove a pump and a string of sucker rods in order to gain access to the sediments. It is also especially troublesome in offshore and other high cost operations where any down time in production becomes very expensive.
In many petroleum producing operations, especially those located offshore, it is a common practice to drill wells which have a generally vertical upper component or section and a generally lateral or horizontal lower component. Thus, a well may start off vertically from the surface of the earth and then angle or curve off to a lateral disposition. The well is generally cased and cemented and then perforated in the producing zone to obtain production. In some instances, it is necessary or desirable to stimulate the well by steaming, acidizing, fracturing or the like through the perforations. It is also sometimes necessary or desirable to inject steam, solvents, water or other fluids through the perforations in order to drive petroleum in the producing zone toward a spaced well. It is desirable in all such operations to have a well completion system which is reliable and flexible, and which allows ready cleaning of the well. This is especially the case when the well is a pumping well wherein a downhole pump serves to pump produced fluids up the well.